The present invention is a process for the preferential production of methyl formate by the catalyzed gas reaction of carbon monoxide and hydrogen. This may be expressed as the reaction of synthesis gas under influence of a homogeneous catalyst to carbonylate and produce methyl formate. This reaction is conducted under relatively low temperature, 50.degree.-150.degree. C., and relatively low pressure, .gtoreq.100 psi.
Two predominantly superior gas reactions are involved in the catalyzed synthesis gas reaction and the equations for these two reactions are set out below: EQU 2 CO+2H.sub.2 .fwdarw.HCOOCH.sub.3 (methyl formate) EQ. I EQU CO+2H.sub.2 .fwdarw.CH.sub.3 OH (methanol) EQ. II
The purpose of the instant process is to so control the reaction conditions that the production of methyl formate will be preferred to that of methanol, so that methyl formate is the predominant end product produced directly from synthesis gas and not through a methanol intermediate. In the present reaction (I) given an input ratio of about 1:1 for carbon monoxide over hydrogen, the output of methyl formate may range up to 50 percent when calculated in the ratio of methyl formate to methanol. The catalyst utilized here is an alkoxide catalyst, produced from the reaction of an alkali metal hydride with a tertiary alcohol, which is combined with a metal carbonyl. More specifically, the catalyst consists of the complex reducing agent of the formula XH--ROH--M(OAc).sub.2 wherein X is an alkali metal, M is selected from the group consisting of Ni, Pd, and Co and R is a lower alkyl group containing 1-6 carbon atoms, which is incorporated into a system where the second component in the system consists of a metal carbonyl selected from the group VI metals (Cr, Mo, W), with Mo(CO).sub.6 being preferred. This system thus contains the complex reducing agent capable of activating hydrogen for reducing carbonyl bonds, as well as the metal carbonyl which is capable of activating carbon monoxide. The catalyst system may also be designated as XOR/M(CO).sub.n wherein X, R and M are as defined above. A preferred combination utilizes potassium t-amyl alkoxide or t-butoxide with Ni(CO).sub.4 in a solvent such as tetrahydrofuran.
An overall equation expressing the present invention is ##STR1## and the theory of the gas reaction is as follows. The reaction may be described as a method for converting synthesis gas directly into methyl formate at low temperature and pressures utilizing the above described catalyst system. In a typical run where the reactor contains the homogeneous catalyst and said catalyst is pressurized with synthesis gas, co-production of methyl formate and methanol takes place, and a more positive ratio of methyl formate to methanol can be achieved by upgrading the CO in the CO/H.sub.2 ratio in the feed synthesis gas.
In this reaction methyl formate may be synthesized in a one step process directly from synthesis gas and also there may be co-production of methyl formate and methanol which can be realized in one pot with a ratio of the two controllable by varying the CO/H.sub.2 ratio in the feed gas. All of this is accomplished at low temperature, 50.degree.-150.degree. C., and pressures of .gtoreq.100 psi.